1. Field of the Invention
This invention relates in general to computer systems and more specifically to console redirection in computer systems.
2. Description of the Related Art
Remote console emulation of a local console of a computer system such as a server allows a system manager at a remote location to monitor, manage, configure, and trouble shoot the server without having to be physically present at the server location. In remote console emulation, video data such as text and graphics that are displayed on a local monitor are provided to and displayed on a remote monitor for viewing by a remote user such as a system manager. Also with remote console emulation, keystrokes and pointer entries made with a remote keyboard and pointer (such as a mouse) are provided to the server and have the same effect on the server as with keystrokes and pointer entries made by a local keyboard and local pointer device, respectively.
In the past, console redirection has been accomplished by placing a remote video controller on the same computer bus (such as a Peripheral Component Interconnect (PCI) bus) as a local video controller (such as a VGA controller). The remote video controller receives video data by snooping the writes on the computer bus to the local video controller from the system processor. Data from the local controller (such as from the local keyboard) is obtained by trapping or chaining the interrupts from the local video controller to the system processor.
Another technique of console redirection is disclosed in Farrand et al, U.S. Pat. No. 5,440,699. In Farrand, console redirection is accomplished by a system management board or card accessing the video data in the video memory portion of the system memory by bus mastering and providing that video data to a remote monitor.
The above techniques for console redirection require that the video controller for the local and remote video monitors reside on the same computer bus (as with the first technique), that the video data be accessible in the system memory by both controllers, and/or that the video data writes to the local video controller are detectable by the remote monitor video controller.
With the increase in speed and memory of today's computer systems, new standards for providing video data to monitors are being utilized to increase the speed of video data transfers to enable a monitor to display relatively complex graphics such as moving 3-D images. One such standard for increasing the amount of data that can be provided to a monitor is the Accelerated Graphics Port Interface Standard (AGP standard). A description of an AGP standard can be found in the ACCELERATED GRAPHICS PORT INTERFACE SPECIFICATION, Rev 2.0, May 4, 1998, by the INTEL CORPORATION which is hereby incorporated by reference. In a computer system implementing circuitry conforming to the AGP system, video data is obtained by the local monitor connector circuit as per the AGP standard.
One problem of performing console redirection in computer system utilizing AGP compliant components to provide video data to a local monitor is that it is relatively impractical and/or impossible for a remote monitor connector circuit coupled to the computer system via another computer bus (such as a PCI bus) to snoop the video data being provided to the AGP compliant video controller. Typically, video data transfers to an AGP compliant video controller are not seen on the PCI bus.